1. Field of the Invention:
The present invention relates to an optical information recording member which permits a quick recording of optical information at a high density, as well as quick reproduction of the recorded information, by use of light or heat etc.
2. Description of the Prior Art:
There have been publicly known techniques for effecting highly dense recording and reproduction of information by means of laser beam. One of these known techniques employs a recording medium having a thin film essentially comprising TeOx (0&lt;x&lt;2) which is a mixture of Te and TeO.sub.2. Such recording medium is shown in Japanese Patent Laid-Open Publication Nos. 46317/1975, 46318/1975 and 46319/1975, as well as in the specification of the U.S. Pat. No. 3,971,874. In the production of this type of recording medium, PbOx (0&lt;x&lt;1), SbOx(0&lt;x&lt;1.5) or VOx (0&lt;x&lt;2.5) are used as additives. This recording medium can obtain, when scanned with a reproducing light beam, a large change in the transmittance.
However, there is a practical limit in the power of the laser beam source, particularly when there is a demand for miniaturization and simplification of a recording/reproducing device. The recording medium having thin film essentially comprising TeOx (0&lt;x&lt;2) cannot exhibit sufficient sensitivity, when a compact He-Ne laser or laser diode of about 20 mW power is used for effecting the recording/reproducing. When the reproduction is made by virtue of the amount of lange in the quantity of light reflected by the medium, this type of recording medium can not obtain a sufficient amount of change in the quantity of the reflected light.
In order to obviate the above-described problems of the prior art, it has been attempted to lower the threshold temperature for the change of state, by adding a suitable additive of a low melting point to the TeOx (0&lt;x&lt;2) which is the major material of the recording medium. For instance, it has been attempted to add T1Ox (0&lt;x&lt;1.5), typically T1.sub.2 O having a melting point of 300.degree. C., as proposed in Japanese Patent Laid-Open Publication No. 38616/1980.
On the other hand, it has been proposed to increase the refractive index of the medium so as to obtain a greater amount of change in the optical property caused due to change in the state. To this end, it has been attempted to add an additive which has both large ion polarizability and high density such as BiOx or InOx (0&lt;x&lt;1.5), as proposed in Japanese Patent Laid-Open Publication Nos. 38616/1980 and 163638/1980. Owing to these improvements, nowadays, it becomes possible to effect recording and reproduction of information by means of a laser diode.
On the other hand, the current progress in the information-utilizing society requires a higher speed of transmission of information, which in turn requires a higher speed of recording and reproduction of information and, accordingly, a higher recording sensitivity.